FAO/WHO verbatim
Menopause
Nordin, B.E.C., Need, A.G., Morris, H.A. & Horowitz, M. 1999. Biochemical variables in pre- and postmenopausal women: reconciling the calcium and estrogen hypotheses. Osteoporos. Int., 9: 351-357.
Prince, R.L., Dick, I. & Devine, A. 1995. The effects of menopause and age in calcitropic hormones: a cross-sectional study of 655 healthy women aged 35 to 90. J. Bone Miner.Res, 10: 835-842.
Nordin, B.E.C. & Polley, K.J. 1987. Metabolic consequences of the menopause. A crosssectional, longitudinal, and intervention study on 557 normal postmenopausal women. Calcif. Tissue Int., 41: S1-S60.
The most important single cause of osteoporosis – at least in developed countries – is probably menopause, which is accompanied by an unequivocal and sustained rise in obligatory urinary calcium of about 30 mg (0.75 mmol).
Heaney, R.P., Recker, R.R., Stegman, M.R. & Moy, A.J. 1989. Calcium absorption in women: relationships to calcium intake, estrogen status, and age. J. Bone Miner. Res, 4: 469-475.
Nordin, B.E.C. 1997. Calcium and osteoporosis. Nutrition, 13: 664-686.
Because calciumabsorption certainly does not increase at this time – and probably decreases
Nordin, B.E.C. 1997. Calcium and osteoporosis. Nutrition, 13: 664-686.
– this extra urinary calcium represents a negative calcium balance which is compatible with the average bone loss of about 0.5–1.0 percent per year after menopause. There is a consensus that these events are associated with an increase in bone resorption but controversy continues about whether this is the primary event, the response to an increased calcium demand, or both.The results of calcium trials are clearly relevant. Before 1997, there had been 20 prospective trials of calcium supplementation in 857 postmenopausal women and 625 control subjects;these trials showed highly significant suppression of bone loss by calcium.Nieves, J.W., Komar, L., Cosman, F. & Lindsay, R. 1998. Calcium potentiates the effect of estrogen and calcitonin on bone mass: review and analysis. Am. J. Clin. Nutr., 67: 18-24.
Another meta-analysis covering similar numbers showed that calcium supplementation significantly enhanced the effect of oestrogen on bone.
Food and Nutrition Board, Institute of Medicine. 1997. Dietary reference intakes for calcium, phosphorus, magnesium, vitamin D, and fluoride. Washington DC: National Academy Press.
It is therefore logical to recommend sufficient additional calcium after the menopause to cover at least the extra obligatory loss of calcium in the urine. The additional dietary calcium needed to meet an increased urinary loss of 30 mg(0.75 mmol) is 260 mg/day (6.5 mmol/day) (Figure 14), which raises the daily requirement from 840 mg (21 mmol) to 1100 mg (27.5 mmol) and the recommended intake from 1000 to 1300 mg/day (25 to 32.5 mmol/day), which is a little higher than that recommended by the United States and Canada (Table 31 and 32).
Morris, H.A., Need, A.G., Horowitz, M., O'Loughlin, P.D. & Nordin, B.E.C. 1991. Calcium absorption in normal and osteoporotic postmenopausal women. Calcif. Tissue Int., 49: 240-243.
Ebeling, P.R., Yergey, A.L. & Vleira, N.E. et al. 1994. Influence of age on effects of endogenous 1,25-dihydroxyvitamin D on calcium absorption in normal women. Calcif. Tissue Int., 55: 330-334.
Need, A.G., Morris, H.A., Horowitz, M., Scopacasa, F. & Nordin, B.E.C. 1998. Nordin. Intestinal calcium absorption in men with spinal osteoporosis. Clin. Endocrinol., 48: 163-168.
Not enough is known about bone and calcium metabolism during ageing to enable calculation of the calcium requirements of older men and women with any confidence. Calcium absorption tends to decrease with age in both sexes
Bogdonoff, M.D., Shock, N.W. & Nichols, M.P. Calcium, phosphorus, nitrogen, and potassium balance studies in the aged male. J. Gerontol. 1953;8:272-288.
Owen, E.C., Irving, J.T. & Lyall, A. 1940. The calcium requirements of older male subjects with special reference to the genesis of senile osteoporosis. Acta Medica. Scand., 103: 235-250.
but whereas the evidence that calcium requirement goes up at the menopause is strong, corresponding evidence about ageing men is less convincing. Nonetheless, as a precaution we propose an extra allowance of 300 mg/day (7.5 mmol/day) for men over 65 to bring them into line with postmenopausal women (Table 31).
Williams, M.L., Rose, C.S., Morrow, G., Sloan, S.E. & Barness, L.A. 1970. Calcium and fat absorption in neonatal period. Am. J. Clin. Nutr., 23: 1322-1330.
The calcium content of the newborn infant is about 24 g (600 mmol). Most of this calcium is laid down in the last trimester of pregnancy, during which the foetus retains about 240 mg (6mmol) of calcium daily.
Food and Nutrition Board, Institute of Medicine. 1997. Dietary reference intakes for calcium, phosphorus, magnesium, vitamin D, and fluoride. Washington DC: National Academy Press.
There is some evidence that pregnancy is associated with an increase in calcium absorption [associated with a rise in the plasma 1,25(OH)2 D level] (70-72). For a maternal urinary calcium of 120 mg (3 mmol) and a maternal skin loss of 60 mg(1.5 mmol), the absorbed calcium should be 420 mg (10.5 mmol) daily. Even at optimal calcium absorption, the corresponding calcium intake would need to be 940 mg (23.5 mmol)(Figure 17) and the recommended allowance would need to be 1200 mg (30 mmol)(Table 31), which is similar to that proposed by the United States and Canada (Table 32).
Nordin, B.E.C. 1976. Nutritional considerations. In: Calcium, Phosphate and Magnesium Metabolism. Nordin, B.E.C., ed. p. 1-35. Edinburgh: Churchill Livingstone.
The calcium content of human milk is about 36 mg per 100 ml (9 mmol/l.
A lactating woman produces about 750 ml of milk daily, which represents about 280 mg (7.0 mmol) of calcium. For a maternal urinary calcium of 100 mg/day (2.5 mmol/day) and maternal skin loss of 60 mg/day (1.5 mmol/day), the required absorption is 440 mg/day (11 mmol/day) – the same as at puberty. If calcium absorption efficiency is maximal (i.e., 2 SD above the normal mean) – possibly because of the effect of prolactin on the production of 1,25(OH)2D
López, J.M., González, G., Reyes, V., Campino, C. & Díaz, S. 1996. Bone turnover and density in healthy women during breastfeeding and after weaning. Osteoporos. Int., 6: 153-159.
Kent G.N., Price, R.I. & Gutteridge, D.H. 1990. Human lactation: forearm trabecular bone loss, increased bone turnover, and renal conservation of calcium and inorganic phosphate with recovery of bone mass following weaning. J. Bone Miner. Res, 5: 361-369
–the requirement would be about 1040 mg (26.0 mmol) and the recommended intake would be about 1300 mg (32.5 mmol). However, although it is known that bone is lost during lactation and restored after weaning,
Chan, G.M., McMurry, M., Westover, K., Engelbert-Fenton, K & Thomas, M.R. 1987. Effects of increased dietary calcium intake upon the calcium and status of lactating adolescent and adult women. Am. J. Clin. Nutr., 46: 319-323.
early reports that this bone loss could be prevented by calcium supplementation
Prentice, A., Jarjou, L.M.A. & Cole, T.J. 1995. Calcium requirements of lactating Gambian mothers: effects of a calcium supplement on breast-milk calcium concentration, maternal bone mineral content and urinary calcium excretion. Am. J. Clin. Nutr., 62: 58-67.
have not been confirmed in controlled studies. The prevailing view now is that calcium absorption does not increase and may decrease during lactation. It is increasingly thought that lactational bone loss is not a nutritional problem but may be due to parathyroid hormone-related peptide secreted by the breast
Sowers, M.F., Hollis, B.W. & Shapiro, B. 1996. Elevated parathyroid hormone-related peptide associated with lactation and bone density loss. JAMA, 276: 549-554.
and therefore beyond the control of dietary calcium. In view of this uncertainty, we do not at present recommend any extra calcium allowance during lactation; any risk to adolescent mothers is covered by our general recommendation of 1300 mg for adolescents.
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